Lubricant deterioration sensors have conventionally detected the light absorbance of the three primary colors in a visible light passing through a lubricant to determine the deterioration level of the lubricant based on the light absorbance of the three primary colors (see Japanese Patent Application Publication No. 2012-117951).
The lubricant deterioration sensor disclosed in Japanese Patent Application Publication No. 2012-117951 includes a void portion receiving a lubricant, an LED for emitting visible light into the void portion, and a color sensor for receiving light from the LED having passed through the void portion. In the lubricant deterioration sensor, the LED emits light and the color sensor receives the light and outputs a sensing result on a device provided outside.